The processing of hard dental tissues by simultaneous influence of laser radiation and the flow of abrasive particle is shown in U.S. Pat. No. 5,334,016, where a pneumatic system forms an air jet saturated by abrasive material and directs it on an object inside a patient's mount. A disadvantage of this method is the necessity of delivering the abrasive particles through a pipe at very high speed, this causing loss of essential energy by the particles. Therefore, near the tissues, there are particles with kinetic energies that differ considerably, so that only some of them participate in the removal of tissues, enamel and dentin and the remaining particles are stored in the patient's mouth, producing no useful effect. It can also be difficult to completely remove these particles, even with the help of an additional aspiration system.
The application of laser radiation in this prior art method results in a negligible increase in efficiency, since the air-abrasive flow and laser radiation do not interact, but independently produce additive influence so that the efficiency of laser processing is limited by the finite value of reflection and absorption indices of tissues. The removal, cutting, drilling and other specific methods of laser-tissue interaction are also accompanied in a number of cases with increased necrosis.
Another prior art method and apparatus for processing of tissue and other materials uses particles of condensed substance (drops of liquid), which acceleration in the direction of a surface of the material being processed as a result of interaction with electromagnetic radiation directed to the processed surface. The main disadvantage of this technique is the insufficient hardness of liquid particles, so that, even at high speed, they cannot cut most materials, particularly hard materials such as metals, ceramics, enamel or dentin of a tooth, tooth filling or other tooth prosthesis with high efficiency.
A need therefore exists for methods and apparatus for the improved utilizing of both radiation and particles in the efficient and accurate processing of dental materials and of biological tissues.